There are so many factors involved including what niche you're looking to get into. In IM, you could buy a solo ad that directs them to a squeeze page. In another niche like "playing guitar", you may want to invest in some PPC traffic.

Maybe take that and get $100 worth of content written and do some SEO or article marketing.

sixth, I'm currently looking for a few blogs to comment on in
my niche.

and I think theres more, but all of this I'm operating on LESS
than $100.

Here's the deal: You WILL work very, VERY hard to make up
for little capital to get ANY momentum going. It's a price you
pay for working on a tighter budget, but it CAN be done. Just
focus, and you'll do well.

The only thing that *has to* cost you money when creating a list is the autoresponder, web hosting + domain name...

You could create a free report / video to give away and generate all of the traffic for free if you're willing to do the "leg work"...

I think what we have to establish is are you talking about using that $100 to create a free product + squeeze page or are you using that $100 to generate traffic to an existing free product and squeeze page?

If you're talking about using that $100 on advertising. Then you're going to struggle to build a massive list with just $100... You have a few options. $40 for a WSO to promote your freebee. Pay people by the hour to post on forums with your squeeze page link in signature. Twitter blasts of Fiverr users. Pay someone to mail out your offer to their list...

If the $100 means a lot to you, then do the leg work yourself. If not, then you can "begin" to build a list with this outlay but you're going to have to continue funding or do the leg work afterwards to build the list up to something substantial...